1. Field of the Invention
The present invention relates to an image forming apparatus which includes a developing device including a toner bearing member and a toner supply member configured to supply toner to the toner bearing member, the image forming apparatus further including a detection unit configured to detect a capacitance between the toner bearing member and the toner supply member.
2. Description of the Related Art
There are methods for detecting the amount of toner remaining in a developing device used in an image forming apparatus such as an electrophotographic apparatus. Among those is a capacitance detection method which includes detecting a capacitance between two electrodes arranged inside the developing device to obtain information about the amount of the remaining developer.
In particular, when using a developing device that includes a developing roller serving as a toner bearing member and a supply roller including a foam layer serving as a toner supply member, a detection method discussed in Japanese Patent Application Laid-Open No. 2009-265282 may be used. The detection method includes detecting a capacitance between a core of the developing roller and a core of the supply roller to obtain information about the amount of remaining toner.
Such a method can measure the amount of remaining toner by detecting the capacitance between the cores because the amount of the remaining toner in the developing device and the capacitance are correlated with each other. To accurately detect the amount of the remaining toner, the method discussed in Japanese Patent Application Laid-Open No. 2009-265282 includes rotating the supply roller at predetermined speed for a predetermined time before the detection of the capacitance, thereby stabilizing the amount of the toner in the foam layer.
According to the method discussed in Japanese Patent Application Laid-Open No. 2009-265282, the supply roller is to be rotated for a predetermined time to detect the remaining amount. This imposes an extra load on the toner as much as the supply roller is driven, which can promote toner degradation.